Scientists found two mysterious 'ghost' ancestors hiding in our DNA

Researchers identified genetic traces of two previously unknown human lineages in modern human DNA, including a ghost ancestor whose DNA makes up approximately 1% of the modern human genome and interbred with Homo sapiens more than 50,000 years ago in Africa, and a super-archaic ancestor from a lineage dating back 1.8 million years that interbred with Denisovans.

This is genetic evidence of past interbreeding; it does not change our understanding of current human health or evolution, but significantly complicates the known evolutionary family tree.